Digital to analog converters (DACs) are devices for converting a digital input to an analog signal. Often, a binary number, in the form of a multi-bit word, is received by a DAC and converted to an analog signal in the form of current or voltage proportional to the number. For example, audio signals are stored in digital form but are converted to digital signal before being played. Also, data is often converted to analog signals before it is transmitted wirelessly. Switches, a network of resistors, current sources or capacitors may implement this conversion.
A classic current summing DAC uses matched resistors to convert a binary number to a corresponding voltage level, although it is difficult to maintain accuracy over a range of temperatures and as the number of bits per word increase. There are many different types of DACs available, including pulse width modulation, R-2R ladder, Binary Weighted, oversampling and delta sigma (i.e., α-Σ) converters. Each has different strengths and weaknesses. There are often tradeoffs between size, latency, price, required voltage and current inputs, bits, resolution, etc. Oversampling has become increasingly popular in recent years as a method to avoid problems with noise and interference that often arise with conventional converters. However, these gains often require complex and fast digital signal processing stages.
Therefore, DACs employing simpler, lower cost designs which utilize standard digital components would generally be desirable. Using such components to approximate more costly α-Σ converters would also be beneficial. DACs implementing noise-shaping techniques to push noise to higher frequencies, while limiting the required current, would find many uses as well.